The purpose of the program is study of the physical and chemical conditions in combustion systems that lead to the formation of fine organic and inorganic particles and the coating of these particles with organic mutagens that may be present in combustion gases, and to assess the effects of the particles, with and without mutagens, on mutation of a human lymphoblast cell strain. Particles will be generated in furnaces in which soot and/or selected metals, such as cadmium, zinc, manganese and vanadium, are volatilized, oxidized, and possibly sulfated for conditions simulating those encountered during combustion of fuels. On cooling of the combustion gases, selected mutagenitic compounds that can be formed in combustion systems will be condensed on the particles. In a second set of experiments, organic and inorganic aerosols will be formed by combustion of coals and synthetic carbon spheres doped with selected metal-bearing compounds. These particles will also be coated with mutagenic compounds. The physical and chemical characteristics of particles form the two sources to be determined by a number of critical methods. Then particles generated in the equipment will be collected, and the effect of mutagen-particle interaction on mutation of a human lymphoblast strain will be assessed.